Parallel processing isn’t just for supercomputers or GPUs anymore. Computer makers are throwing multiple cores at everything from servers to your printer. But the focus on horsepower misses a crucial problem associated with adding more processors. To really take advantage of them, you have to rewrite your code. As anyone who’s ever hosted a demolition party well knows, you can only throw so many workers at a problem before people start to linger at the edges, swill your alcohol and generally stop helping.